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1.
Quantization rules have been obtained for the Hall conductance of fully occupied Landau subbands of the two-dimensional electron gas with the Dresselhaus spin-orbit interaction in a periodic electrostatic field of a superlattice and a transverse magnetic field. The spin-orbit interaction mixes states of different magnetic subbands and changes the quantization rule for the Hall conductance compared to spinless particles. The calculations have been performed for the two-dimensional electrons in the structures with both a weak (AlGaAs/GaAs) and sufficiently strong (GaAs/In0.23Ga0.77As) spin-orbit interaction and Zeeman splitting. It has been found that the distribution of the Hall conductance among the magnetic subbands depends on the geometric parameters of the superlattices and promptly changes upon the touching of the adjacent subbands in the spectrum. The quantization rule for the Hall conductance in real semiconductor structures with relatively strong spin-orbit interaction has been shown to differ from that calculated by Thouless et al. [Phys. Rev. Lett. 49, 405 (1982)] for the systems without the spin-orbit interaction and Zeeman effect. 相似文献
2.
A number of effects associated with the curvature of the surface on which a two-dimensional (2D) electron gas is placed are
studied. The most significant effect in an external magnetic field (which for 2D electrons becomes effectively nonuniform)
is the lifting of the degeneracy of the Landau levels. The intensity and shape of the cyclotron resonance line (inhomogeneously
broadened) for different polarizations and the corrections to the Hall constant are found for the example of a circular cylinder.
A picture of the quantization of the conductance that is qualitatively different from the case of a flat strip is obtained
for a quasi-one-dimensional quantum wire in the form of a hollow cylinder. It is shown that in contradistinction to the planar
case the spectrum of 2D electrons on the curved surface is sensitive to the sign of the spin-orbit coupling constant (for
a fixed sign of the curvature). For hetero-junctions, for example, this opens up new possibilities for extracting information
about their “hidden parameters.”
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 6, 421–426 (25 September 1996) 相似文献
3.
V. Ya. Demikhovskii A. A. Perov 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(2):223-225
The Hall conductance of a two-dimensional electronic system with Rashba spin-orbit coupling in the presence of an external periodic potential of a superlattice and a perpendicular magnetic field has been calculated. The calculations were performed for an electron gas with parameters typical both of a system with weak spin-orbit coupling (AlGaAs/GaAs) and a system with relatively strong Rashba coupling (InGaAs/InAs). 相似文献
4.
JETP Letters - Quantization rules have been obtained for the Hall conductance of fully occupied Landau subbands of the two-dimensional electron gas with the Dresselhaus spin-orbit interaction in a... 相似文献
5.
V. Ya. Demikhovskii A. V. Telezhnikov 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(7):919-921
The electron energy spectrum and conductance in a quasi-1D channel with spin-orbit coupling is calculated. The channel is divided into two parts by a potential barrier. It is shown that a change in the barrier electric potential yields additional extema of the function ?(k). This results in modification of the conductance quantization law. The quantum states and conductance are calculated for the parameters of real structures with weak both and relatively strong spin-orbit coupling. 相似文献
6.
Spin relaxation in a two-dimensional electron gas (2D EG) is treated as the establishment of equilibrium in a gas of spin
excitons as a result of processes that change the number of spin excitons. Coalescence is the dominant channel above a temperature
of the order of 1 K. The coalescence of excitons can occurr as a result of spin-orbit and Coulomb interactions in the 2D EG.
The rate of coalescence falls exponentially at low temperatures. The relaxation time is calculated, and the critical temperature
below which the main annihilation process becomes that due to the exciton-phonon interaction is determined.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 8, 531–536 (25 October 1999) 相似文献
7.
We report the experimental observation of impurity-induced conductance dips in quantized channels as predicted by previous theorical studies. Our experiments use quantum point contacts on a two-dimensional electron gas in a modulation-doped GaAs/AlGaAs heterostructure. The electron gas has a sheet density of 1.2 × 1011 cm−2 and a mobility of 4.6 × 105cm2/Vs, measured at 50 mK. Our data, which are qualitatively very similar to those calculated using a two-dimensional Anderson model, strongly suggest that we are observing both the erosion of conductance quantization, and localization in the presence of an impurity-induced random potential. 相似文献
8.
C. Bai Y. -L. Yang X. -D. Zhang 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,65(1):79-84
Based on the extended Blonder-Tinkham-Klapwijk (BTK) approach, we have investigated the coherent quantum transport in two-dimensional
electron gas/superconductor (2DEG/SC) double tunneling junctions in the presence of the Rashba spin-orbit coupling (RSOC).
It is found that all the reflection coefficients in BTK theory as well as conductance spectra oscillate with the external
voltage and energy. The oscillation feature of conductance can be tuned largely by the RSOC for low insulating barriers, while
for high insulating barriers it is almost independent of the RSOC. These phenomena are essentially different from those found
in ferromagnet/superconductor double tunneling junctions. 相似文献
9.
O. Rousière D. Lemoine H. Folliot S. Hinooda R. Granger 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,11(3):491-496
Strong oscillations on capacitance and conductance have been observed in p-type Hg0.8Zn0.2Te metal-insulator-semiconductor structures, made by using a recent process for the interface passivation. This behaviour is
attributed to a two-dimensional electron gas in the n-inversion layer and the variation of the conductance maximums with temperature
indicates that the dominant perpendicular transport mechanism for electrons is an incoherent two-step tunnelling through deep
levels in the gap. Three models have been used to describe the quantum confinement: the simple variational method, the triangular
potential approximation and the propagation matrix method. The later approach takes into account the non parabolicity of the
conduction band structure and uses a finite height barrier at the insulator-semiconductor interface. A very good agreement
between experimental and calculated values for the two lowest subband energy is obtained.
Received 9 February 1999 相似文献
10.
We theoretically investigate the ballistic conductance of hollow quantum wires made of a two-dimensional electron gas occupying a cylindrical surface. The dependence of the conductance on the electron Fermi momentum differs drastically from the conventional case of a strip-like wire. We trace the evolution between these two cases in an exactly solvable model of a circular cylinder affected by a δ-like potential barrier along its element. We consider also a cylinder with two diametrically opposite δ-function barriers, the case representing somewhat realistic semiconductor structures. The general consequences of the boundary condition topology are also discussed. 相似文献
11.
We theoretically studied the spin-dependent charge transport in a two-dimensional electron gas with Dresselhaus spin-orbit coupling (DSOC) and metal junctions. It is shown that the DSOC energy can be directly measured from the tunneling conductance spectrum. We found that spin polarization of the conductance in the propagation direction can be obtained by injecting from the DSOC system. We also considered the effect of the interfacial scattering barrier (both spin-flip and non-spin-flip scattering) on the overall conductance and the spin polarization of the conductance. It is found that the increase of spin-flip scattering can enhance the conductance under certain conditions. Moreover, both types of scattering can increase the spin polarization below the branches crossing of the energy band. 相似文献
12.
The results of an investigation of the width of the electron and hole spectral functions in an isotropic electron gas with
the Rashba spin-orbit interaction as a function of the wave vector within the G
0
W
0 approximation are reported. This kind of electron gas is used to simulate two-dimensional systems formed by electrons in
In
x
Ga1 − x
As layers of various heterostructures and by surface electron states on Au(111). It is demonstrated how the width of the spectral
function changes as a result of the spin-orbit interaction and how it depends on the branch index of the energy spectrum split
by this interaction. 相似文献
13.
《Superlattices and Microstructures》1998,23(6):1227-1230
We theoretically investigate the ballistic conductance of hollow quantum wires made of a two-dimensional electron gas occupying a cylindrical surface. The dependence of the conductance on the electron Fermi momentum differs drastically from the conventional case of a strip-like wire. We trace the evolution between these two cases in an exactly solvable model of a circular cylinder affected by a δ-like potential barrier along its element. We consider also a cylinder with two diametrically opposite δ-function barriers, the case representing somewhat realistic semiconductor structures. The general consequences of the boundary condition topology are also discussed. 相似文献
14.
P. Liu S.-J. Xiong 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(4):513-516
The spin Hall transport properties in a two-dimensional electron
system with both Rashba spin-orbit coupling (SOC) and magnetic
impurities are investigated. Electrons are scattered by impurities
through an exchange interaction that leads to spin flip-flop
processes and so changes the spin Hall effect induced by the SOC.
The spin Hall conductance is calculated in a 4-terminal system
using the Landauer-Buttiker formula and Green function approach.
In comparison with the simulation results on nonmagnetic
impurities doping systems, our results reveal that the spin Hall
conductance is still nonzero in a system with a large density of
magnetic impurities and a finite intensity of the exchange
interaction between the electrons and impurities, and its sign may
be altered when the doping density and interaction strength are
large enough. 相似文献
15.
V. Ya. Demikhovskii A. V. Telezhnikov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(3):423-431
The electron energy spectrum and wave functions for a quasi-one-dimensional channel with Rashba spin-orbit coupling are calculated.
The dynamics of wave packets in thin wires based on GaAs/In0.23Ga0.77As and AlGaAs/GaAs heterostructures with Rashba spin-orbit coupling are studied. Spin polarizations are found. The effect
of splitting of wave packets with respect to their centers of mass and Zitterbewegung of their centers are discovered. The
characteristics of wave-packet oscillations and spin density for free electrons and under confinement conditions are compared.
A method for controlling the conductance of the quasi-one-dimensional channel using a controlling electrode is proposed. 相似文献
16.
M. M. Gelabert L. Serra 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,79(3):341-349
We investigate the linear conductance of a stripe of spin-orbit interaction
in a 2D electron gas; that is, a
2D region of length l\ell along the
transport direction and infinite in the transverse one in which a spin-orbit
interaction of Rashba type is present.
Polarization in the contacts
is described by means of Zeeman fields.
Our model predicts two types of conductance oscillations:
Ramsauer oscillations in the minority spin transmission, when both
spins can propagate, and Fano oscillations when only one
spin propagates.
The latter are due to the spin-orbit coupling with quasibound
states of the non propagating spin.
In the case of polarized contacts in antiparallel configuration Fano-like oscillations
of the conductance
are still made possible by the spin orbit coupling, even though no spin component
is bound by the contacts.
To describe these behaviors we propose a
simplified model based on an ansatz wave function.
In general, we find that the contribution for vanishing transverse momentum dominates
and defines the conductance oscillations.
Regarding the oscillations with Rashba coupling intensity, our model confirms the
spin transistor behavior, but only for high degrees of polarization.
Including a position dependent effective mass yields additional
oscillations due to the mass jumps at the interfaces. 相似文献
17.
The spin Hall effect in a two-dimensional electron system on honeycomb lattice with both intrinsic and Rashba spin-orbit couplings is studied numerically. Integer quantized spin Hall conductance is obtained at the zero Rashba coupling limit when electron Fermi energy lies in the energy gap created by the intrinsic spin-orbit coupling, in agreement with recent theoretical prediction. While nonzero Rashba coupling destroys electron spin conservation, the spin Hall conductance is found to remain near the quantized value, being insensitive to disorder scattering, until the energy gap collapses with increasing the Rashba coupling. We further show that the charge transport through counterpropagating spin-polarized edge channels is well quantized, which is associated with a topological invariant of the system. 相似文献
18.
A generalized finite element formulation is proposed for the study of the spin-dependent ballistic transport of electron through the two-dimensional quantum structures with Rashba spin-orbit interactions (SOI). Thetransmission coefficient, conductance, the total and local polarization are numerically calculated and discussed as the Rashba coefficient, the geometric sizes, and incident energy are changed in the T-shaped devices. Some interesting features are found in the proper parameter regime. The polarization has an enhancement as the Rashba coefficient becomes stronger. The polarization valley is rigid in the regime of the conductance plateaus since the local interference among the polarized multi-wave modes. The Rashba interactions coupling to geometry in sizes could form the structure-induced Fano-Rashba resonance. In the wider stub, the localized spin lattice of electron could be produced. The conductance plateaus correspond to weakpolarizations. Strong polarizations appear when the stub sizes, incident energy, and the Rashba coupling coefficient are matched. The resonances are formed in a wide Fermi energy segment easily. 相似文献
19.
A microscopic theory of superconductivity is developed for the magnetized electron gas on a cylindrical surface. The Gibbs free energy is calculated for the superconducting system. A gap equation is derived that determines the critical temperature as a function of the quantum-cylinder dimensions and the Aharonov-Bohm parameter. It is shown that the gap not only exhibits Aharonov—Bohm oscillations, but also oscillates with varying curvature of the cylindrical surface. 相似文献
20.
We show that with interface spin-orbit coupling, triplet pairing can occur in the
half-metal/superconductor junction. The tunneling conductance is different from the usual
Andreev reflection and strongly depends on the polarisation orientation. The probability
of triplet pairing for different incident angles and zero-biased conductance are also
calculated. The mechanism for the formation of the triplet pairing is that the interface
spin-orbit coupling provides an effective spin-flip barrier, which couples all the
transport modes in spin Nambu space. Because of its unique particle hole symmetry, this
spin-orbit coupling interface effect is different from the spin-flip ferromagnetic barrier
which induces zero-bias conductance vanishing and finite V-shape
conductance within the energy gap. 相似文献